I intend to attend an international conference in Taiwan this September and was looking into the visa procedure for the same. The website (https://www.boca.gov.tw/cp-152-274-8c0e2-2.html) says that if I have a "valid entry visa" to US, I can apply for an e-visa, which seems to be an easier way out. I do have a valid B-1/B-2 visa and a J-1 visa that expired 7-8 months ago, but I've never heard the term "entry visa" before. A google search doesn't explain anything either. Therefore, what exactly is an "entry visa"?
An "entry visa" is just a visa which permits you to travel to the named countries.
It is written this way to distuingish it from the "exit visa", which is a document that a few countries still use, which is required for a person to leave those countries.